A mechanical filter can be used to remove, filter, or collect particles. This filtering and collection of particles can be used for sampling of particles, chemical detection, and/or biological cell analysis.
One of the most important determinants of prognosis and management of cancer is the absence or presence of metastatic dissemination of tumor cells at the time of initial presentation and during treatment. The early spread of tumor cells to lymph nodes or bone marrow is referred to as circulating tumor cells (CTC) when in the peripheral blood. It has been well established that these CTC can be present even in patients who have undergone complete removal of the primary tumor. The detection of CTC has proven to be a useful tool in determining the likelihood of disease progression.
CTC exist in blood on the order of 1 per 10 billion blood cells. Currently available technologies are inadequate to identify circulating tumor cells with requisite sensitivity, efficiency and specificity. The present techniques including density gradient separation, immunomagnetic separation and density gradient immunomagnetic separation filtration used for CTC capture and identification require multiple procedural steps, handling of relatively large volumes of sample, substantial human intervention, are labor intensive, are extremely high cost and lack reliability and standardization for the detection methods. Commercial filtration systems have low efficiencies. Commercial membrane filters, such as polycarbonate filters, show randomly and sparsely distributed holes, with many noticeably fused, resulting in larger openings. Therefore, it is clear that the development of a device capable of detecting the earliest metastatic spread of tumor in the peripheral blood can revolutionize the approach to the disease management.
Since the average size of CTC's for most common epithelial cancers is significantly larger than most blood cells, separation based on size can be very effective. Membrane filter allows the processing of a large volume of blood and parylene provides a unique filter substrate due to its processability, stability, flexibility and biocompatibility. Therefore, it is desirable to develop a filtration system to overcome the above and other problems, in particular, for the efficient capturing and detecting of extremely low concentration of cancer cells in the blood.